There is an urgent need for low-cost temporary structures to house people and animals in the event of natural disasters and for refugees from conflict areas, not only for housing, but also for medical triage, food preparation and supplies storage. Although tents are the currently-used solution, they are inadequate for a wide range of reasons, including low internal height, relatively short life, relatively frangible, relatively impermanent in inclement weather, not insulated, subject to collapse in heavy snow-load environments, and for the more sophisticated, advanced material type of expedition tents, much too expensive.
In cases of natural disaster, there is an immediate unmet need for longer term useable structures, having a useful-life of on the order of 2-6 years until permanent housing is constructed for the homeless. A prime example is the 2004 Christmas tsunami that developed from a 9.1 magnitude sub-sea earthquake off the SW coast of Sumatra. The earthquake triggered a series of devastating tsunami along the coasts of most landmasses bordering the Indian Ocean, killing more than 225,000 people in eleven countries, and inundating coastal communities with waves up to 30 meters (100 feet) high. It was one of the deadliest natural disasters in recorded history. Indonesia, Sumatra, Sri Lanka, India, and Thailand were hardest hit.
Similar disaster examples are the refugee situations resulting from the magnitudes 7.1 and 6.0 Haiti earthquakes of Jan. 13 and 19, 2010, the 9.0 Sendai-Japan earthquake followed by monster tsunami on Mar. 11, 2011, and those resulting from the conflicts in Gaza, Somalia, Libya and the ethnic wars in various African countries. In all there total millions of displaced persons living in the open or in frayed tents in refugee camps, or huts of mud and dung wattle, discarded sheet metal, cardboard and worn sheets.
Even more prevalent are the estimated 1 billion squatters and homeless in the world. In almost all of the world's countries there are extensive slums, favelas, barrios, or shanty towns, typically on the edges of major cities and consisting almost entirely of self-constructed housing built of scraps of material without the landowner's permission. While these settlements may in time grow to become both legalized and indistinguishable from normal residential neighborhoods, they start off as “squats” with minimal basic infrastructure: no sewage system or drinking water, and if there is electricity, it is stolen from a nearby cable.
Temporary shelters are also used at conventions, trade shows, fairs and festivals, sporting events, for farm stands, and along trails or at camp grounds, to name a few.
There have been a number of design attempts in the prior art for temporary, rapid construction, light weight or field shelters, among them being: Zwern US Published Application 2009/0272-043 disclosing hexagonal yurts that can be clustered, made of corrugated, foam core, Al-faced poly-isocyuranate panels. Both the side walls and roof are each made of one continuous panel. There is no roof or gutter overhang, and the roof is glued to the walls, and a cable is used to form tension rings top and bottom to hold it together. A complex cross-rib foundation system is used to support the floor. Since the walls and roof are multiple continuous perimetral panels, this structure is not easily man-portable for field erection as a temporary shelter.
Pascoe U.S. Pat. No. 5,319,904 discloses a clusterable prefab structure using arcuate surface panels to form a frustrum. Uses inner and outer fiberglass or Kevlar layers that are insulated between with foamed-in polyurethane. The structure appears to have primarily military use, in which the adjacent side wall, roof and floor panels are hermetically sealed by inter-engaging dados and grooves cinched together by external flanges and bolts, top and bottom.
Sadler U.S. Pat. No. 5,184,436 shows a portable rectangular structure of the Dutch barn style, having a slant roof and central ridge made of a continuous, multi-panel sheet forming both side walls and roof, with separate end panels. The sheet material is corrugated extruded polyethylene, and the two inwardly slanted side panels include exterior flaps that serve as hold-downs by use of sandbags. A yurt-type structure is not disclosed, nor is the structure easily clusterable.
Monson U.S. Pat. No. 6,658,800 discloses a dome made of a plurality of quadrilateral compound convex panels. They are double-walled panels, thermoformed of high-density polyethylene, which are joined at a lip-seam edge.
Yacoboni U.S. Pat. No. 4,784,172 discloses an emergency shelter of three-section combined wall and roof panels forming a pointed-top dome made of single layer corrugated plastic, held together with clips securing adjacent panels along external flanges/ribs. A box and support belt assembly may be used by a man carrying a bundle of the pre-folded panels into the field.
More complex and less pertinent ideas are illustrated in still other patent references; Tuczek U.S. Pat. No. 6,282,849 being directed to a highly complex exercise in proposing polyhedron dome buildings made of triangular panels interspersed with, and connected to, prismatic beams. The panels and beams are not for temporary, field erectable structures, being proposed as concrete beams supporting SIP panels of plywood with foamed interior layers.
Andrieux U.S. Pat. No. 5,715,854 discloses an igloo made of bowed panels pleated at the upper edge to compensate for curvature deformation. The panels are single-layer and connected by side edge, ball-and-socket connectors. The roof dome top is a single convex piece.
Daugherty U.S. Pat. No. 4,073,105 discloses a toy or display structure formed of trapezoidal or triangular structures made of single piece, rigid plastic or metal panels, having curled edges that slidingly interlock. A single roof panel having creases forming edges of a shallow pyramid is provided.
Murdock U.S. Pat. No. 6,085,485 discloses steel SIPs formed of two spaced sheet steel sheets (skins) having Z or C internal connecting ribs with insulation provided between the two skins. Overlapping edges of panels are connected by self-sealing Tek fasteners.
Ferguson U.S. Pat. No. 6,598,363 discloses a modular single ridge barn-like structure made of corrugated single-layer panels having side edge margins that include alternating tabs and eyes for linking panels together along the edges. Prefab eave and ridge beams having holes and pegs join a gable roof made of the same panels to the vertical side walls. Although no materials are specified, the corrugated form of the sheets appear to be steel, aluminum or fiberglass.
Icosa Village U.S. Pat. No. 6,895,772 is directed to multiple panels folded into modular polygonal beams that interlink, first into triangular modular double-walled panels, and in turn the triangular panels are assembled into icosahedral dome structures. Tetrahedral windows may be inserted in the center opening of the triangular modules.
Finally, Domes for the World, (177 Dome Park Place, Italy, Tex., 76651), discloses its mission is to provide low cost, rebar-reinforced, permanent concrete dome shelters for third-World regions. The DFTW system uses an air inflated dome atop cylindrical wall forms that are sprayed with concrete over rebar to make a monolithic shell.
While these approaches suggested in the prior art are interesting, for the most part they are complex, not light-weight or modular enough to be simply portable, do not address all the needs of a semi-permanent, sound, fully functional shelter, that is simple to install in the field by unskilled workers, yet results in a highly robust structure that is clusterable into a wide variety of configurations to provide for a wide range of needs over many years of use.
Accordingly, there is a pressing need for improvements in rugged, temporary shelters that are low cost, simple to manufacture, light weight for easy portability to an erection site, simple to erect by unskilled manual labor without complex tools, yet are weather and pest-proof and flexible in design to provide cluster-buildings for a wide range of housing and support uses for extended service life. Perhaps most importantly, the structures should not be limited to round-footprint, non-expandable structures, but rather should have provision for expandability as needs and uses dictate.